How many foci does a parabola have?

Answer 1

A parabola has a single focus point. There is a line running perpendicular to the axis of symmetry of the parabola called the directrix. A line running from the focus to a point on the parabola is going to have the same distance as from the point on the parabola to the closest point of the directrix.

In theory you could look at a parabola as being an ellipse with one focus at infinity, but that really doesn't help any. ■